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configuring NTP

I would like to configure my 3750 switch as NTP server and synchronise for few windows servers

what all commands should i use

Any help on this

rgds/shiva

16 REPLIES

Re: configuring NTP

set switch to be ntp master ,

NTP master startum X ( X could equal 7 as an example)

http://www.cisco.com/en/US/docs/ios/12_1/configfun/configuration/guide/fcd303.html#wp1001170

HTH

Pls rate helpful posts

Sam

Hall of Fame Super Gold

Re: configuring NTP

Shiva

If the switch is not learning time from some NTP server then Sam is correct that configuring the switch with ntp master will set the switch as an NTP server. This means that the network will be dependent on the accuracy of the clock in the switch. If the switch can learn NTP time from some server it would be more accurate. And if the switch is learning NTP time from some server then it is automatically set up to serve time to other devices and you do not need ntp master.

One other aspect of this involves the switch providing time to Windows servers. Windows uses a slightly different protocol than NTP by default. And unless you are running some application on them to utilize NTP they will not send NTP requests to the switch. You might try configuring ntp broadcast on the switch layer 3 interface for the PCs which will cause the switch to send NTP broadcasts which the PCs may process.

HTH

Rick

Community Member

Re: configuring NTP

thanks richard,sam

rick,I am frequent user of cisco forum and

i found several posts by you with clarity. I am very happy to see reply from u

I am stuck in urgent situation to configure

3750 switch as NTP server and some windows servers has to synchronise with switch to get proper time,i havent used NTP configuration before,i need basic commands in simple way i should put,since the documents sam provided i have come across before from which i couldn't understand properly

"I need only commands to make this work"

any one can you help on this

Rgds/Shiva

Community Member

Re: configuring NTP

any expert,

solution for this ?

is it best to synchcronise time from internet atomic time servers for NTP or what is the normal way of doing it

or setting it up manually on the switch the

timings

rgds/shiva

Hall of Fame Super Gold

Re: configuring NTP

Shiva

I would say that the more common way is for devices to leaern NTP time from an external NTP server. If you want to find an external NTP server that you can use then this link will point you to a list of them:

http://support.ntp.org/bin/view/Servers/WebHome

Sam was correct in his suggestion that the most simple and direct solution is to configure the switch as an NTP server using the command ntp master 7. If you do this the switch will use its own clock, which you should make sure is set to the correct time. You could also configure ntp broadcast on the VLAN interface for the subnet(s) where the Windows servers are connected. Give that a try and let us know how it works.

HTH

Rick

Community Member

Re: configuring NTP

thanks rick

but if i put the command ntp master 7 -it will use the timing from the local switch

then how will it synchronise with external NTP servers on the internet

will it synchronise or not

rgds/shiva

Re: configuring NTP

it won't sunch with internet.

Switch becomes the master Clock, and relies on its own clock ( as started by Rick in previous replies).

If u servers are dependant on a reliable and guenuine NTP master, u need external clock.

HTH

Sam

Community Member

Re: configuring NTP

so what is the command to syncronise with

internet ntp servers (external ntp)

from the list of servers available which i should use ,is there any command i should use for daylight changes.

rgds/shiva

Re: configuring NTP

ntp server x.x.x.x where x.x.x.x is the address on a server u can reach.

for clock settings, see below exmaple:

this changes clock between summet time and winter time.

clock summer-time CEST recurring last Sun Mar 2:00 last Sun Oct 3:00

HTH

Sam

Community Member

Re: configuring NTP

hi,

so to configure my switch to fetch time from internet ntp server should i use

switch#ntp server x.x.x.x (x.x.x.x is the ip address of internet ntp server.

rgds/shiva

Re: configuring NTP

yes !

assuming you can reach the address, and allowed to synch from it.

Sam

Community Member

Re: configuring NTP

thanks sam,

so my configuration would be if synchronise nasa ntp server od stratum 1

switch#ntp master stratum 2

switch#ntp server 198.123.30.132(nasa ntp server)

is it right

rgds/shiva

Community Member

Re: configuring NTP

is the configuration mentioned above i should use to synchronise with internet NTP server.

rgds/shiva

Community Member

Re: configuring NTP

Shiva,

If you synchronizing the switch with an external server, you need not configure the switch as an ntp master.

That command is very much used if you using the switch as a stand alone server and nothing else.

-/ KC

Community Member

Re: configuring NTP

hai cherian,

so if i put

switch#ntp server x.x.x.x (x.x.x.x-ip address of the internet server)

is it ok.will it get syncronised with the sever for atomic clock.

rgds/shiva

Community Member

Re: configuring NTP

Yes, it will, as long the server is reachable via that switch and that those NTP packets on port 123 are not blocked.

-/ KC

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